266 AMERICAN JOURNAL 



The specimen figured is the only one I have seen, and belongs 

 to the collection of the Smithsonian Institution. 



PL 20, fig. 3. Young shell of Sycotypus canaliculatus before 

 exclusion from the pouches. Enlarged. 



PI. 20, fig. 4. Young of Busycon aruanum, enlarged. 



The former shell is entire ; the latter has a longitudinal fissure 

 on the body whorl which divides the columella, and it is 

 covered by so delicate a membrane that it is generally broken or 

 absent. If this difference should be found to exist in all the 

 young species of the two genera, it will confirm the generic dis- 

 tinction. 



B. DUMOSUM. — PI. 19, fig. 3. 



Description. — Fusiform, rather thick in substance ; whorls 7 ; 

 slightly concave above ; spire prominent, angle near the suture, 

 carinated and tuberculated on the smaller volutions and spin- 

 ous on the back of the penultimate whorl ; body whorl with 

 prominent, distant spines, not dilated at base ; surface with 

 prominent filiform revolving lines, with very minute interme- 

 diate lines, generally three in number ; body whorl rather ab- 

 ruptly rounded or subangular inferiorly where there is a space 

 without revolving lines, but longitudinally subcostate ; beneath 

 this space the shell has more prominent, closer rugose lines ; 

 aperture with sharp prominent lines within, terminating in irreg- 

 ular, more elevated and thicker rib-like lines. 



B. FILOSUM, Conrad. — PI. 21, fig. 7. 



Proceed. Acad. Kat. Sciences, 1862, p. 286. 



The figure represents a small specimen. It attains to Qh inches 

 in length. 



B. CONTRARUM, Conrad. — PI. 23, fig. 2. 



Observation. — This species has been referred to B. perversum, 

 Lin., but it is greatly inferior in size, and, except in its reversed 

 aperture, has no very near affinity with that species. 



Fiilgur contrarius, Conrad. American Journ. of Science and 

 Arts, vol. xxxix. p. 387. 



Busycon contrarium^ Conrad. Miocene Fossils, pi. 45, fig. 11. 



B. TUBERCULATUS. — PI. 23, fig. 1. 



Fulgur tuberculatus, Conrad. Bulletin of the National Insti- 

 tution, p. 185. 



Busycon tuberculatus. Miocene Fossils, pi. 46, fig. 2. 



